Volumen 72 (2022): Edición 3 (November 2022)

Faculties of Mechanical Engineering, especially their Departments of Internal Combustion Engines, began conferences with a later designation KOKA (or KoKa) in the year 1969. These were initially focused on the research of the combustion engines. This was later accompanied also by research of the vehicle powertrains and drive units in general. Latest of these conferences was organized by the Institute of Transport technology and Engineering Design, SjF, STU in the year 2022 in the mansion house Kočovce.

The presented article deals with the possibility of using synthesis gas produced from municipal waste in a spark-ignition combustion engine intended for a micro-cogeneration unit. The subject of investigation is the effect of fuel composition on the internal parameters of the internal combustion engine analysed from the course of pressure in the cylinder. The analysis shows that, in general, increasing the proportion of hydrogen increases the pressure rise rate as well as the rate of heat release in the cylinder. The presented results will serve to understand the processes taking place in the combustion engine as well as the importance of the composition of synthesis gas produced from renewable energy sources in order to achieve the highest possible energy and economic evaluation in the cogeneration unit.

Investigation of road vehicles in term of their dynamics is very important task. There are assessed two main points of view, i.e. the driving safety and ride comfort for passenger. This article is aimed at analysis of dynamics of a single-axle trailer by means of real tests. Several driving manoeuvres have been performed and evaluated, at which, when a trailer has been towed by a passenger car. As the main output parameters, acceleration signals have been measured and recorded. The vehicle-trailer combination has been moved at several driving speeds.

This article describes the testing of oil filters on a laboratory test device designed to monitor changes in oil filter flow and pressure, depending on the level of engine oil contamination. The laboratory test device enables testing the suitability of using filters with different filtering capabilities, even with differently polluted engine oil. The measurement results can be used in the design of new filter materials, or in the design of changing replacement intervals, which would mean a benefit from an economic as well as an ecological point of view.

The automotive industry is exposed to continued pressures, the goal of which is decarbonisation together with application of the advanced technologies and fuels, as well as utilization of the alternative vehicle drives. The main task of the scientific publication was a complex emission analysis of the selected vehicles during various test cycles, as well as a comparison of the individual emissions when using different types of fuel.

The current standard methods of determining the mechanical losses of the ICE by motoring do not correspond to the low pressures in the cylinders of real engine operation. The new tried and tested method of determining passive resistances by motoring ICE with high working pressures in the cylinders is based on blowing doses of compressed air into the cylinders around BDC with special self-acting valves. When motoring with the new method, the same course of pressures in the cylinders and the same load on the crank mechanism, including the piston group, is achieved during combustion. The measurement proved the problem-free functionality of the self-acting valves, and the conducted experiments provided data on the dependence of mechanical and heat losses in the ICE on the working pressures in the cylinder.

This paper presents a new 4-lobe blower for supercharging a two-stroke engine. Based on a modified Roots compressor manufactured prototype shows pros and cons of an innovative profile. The results demonstrate that the shape of rotor edges effect out pressure stability. The measurement results include the main assessed parameters: outlet pressure, overall efficiency, losses and outlet air temperature.

Greenhouse gases jeopardize world’s climate. A significant amount of these pollutants is produced by road vehicles, so their producers are forced to reduce their emissions significantly. This means that every car manufacturer is expanding their electrified vehicle range. Fully electric vehicles are the best way for long-term elimination of greenhouse gases production in road transport. However, in the short term it is not possible to switch all vehicles to EVs. Temporary solutions are hybrid electric vehicles, which offer a compromise between conventional and electric vehicles. In addition to the right choice of hybrid powertrain and correct scaling of its components, it is also important to develop a suitable control strategy for its energy management. The main goal of this work is to compare the performance of the rule-based control strategy with the built-in local optimization algorithm ECMS in GT-SUITE^TM software. ECMS means Equivalent Consumption Minimization Strategy and is based on an optimization of selected control parameters in each time step of the driving cycle simulation. A fuel efficiency improvement is assessed on a selected plug-in hybrid vehicle. Results of WLTC driving cycle simulations in charge sustaining mode (state of charge of the battery at the beginning and at the end of the simulation is the same) shows fuel consumption of 5 l/100km for rule based control strategy and 4.2 l/100km for ECMS algorithm. This means that ECMS can achieve more than 16% improvement for this particular vehicle.

The overall efficiency of high-speed rotating machines depends largely on their mechanical efficiency. Mechanical efficiency is not just a matter of bearing losses, but includes all interactions of the rotor with the environment. Analytical and empirical descriptions of turbulent or laminar flow around rotating surfaces have been used to estimate the mechanical losses of a turbocharger rotor based on geometric parameters and operating conditions. Based on the knowledge of the effect of each parameter, design changes to the rotor were proposed. The positive effect of simple design modifications on mechanical losses was experimentally verified by measurements on a test turbocharger.

This paper describes a possible approach of designing an unconventional turbocharger using co-simulation method. Our goal is to design turbochargers running optimally during pulsating and transient modes. It means to develop a tool capable of co-simulation between 3-D and 1-D CFD. This tool must be fast and precise enough and provide a reliable result. Influence of a coarse mesh versus fine mesh was examined. Different time step size was applied to determine calculation sensitivity. Different types of turbines were tested.

Parallel hybrid electric vehicle (HEV) powertrain topologies are easily applicable on an existing conventional powertrain, and are frequently used in passenger vehicles, with a goal to reduce the overall fleet CO₂ emissions, either with mild, full, or plug-in capability. However, for the heavy-duty trucks, the powertrain electrification progresses more slowly. Therefore, the goal of this paper is to evaluate three different hybridization options, together with two electrification options, in comparison with conventional powertrain combined with 5.9 L 6-cylinder diesel internal combustion engine in a heavy-duty 7.5-ton application. All vehicle variants are evaluated in eight vehicle driving cycles replicating different heavy-duty use-cases at different cargo levels, also considering the economical aspect of these different electrification options, calculating the payback periods for each powertrain option. The energy management control strategy, that determines the power split between the ICE and electric motor for HEV variants is an optimal one, based on Pontryagin’s Minimum Principle. All models are programmed in-house in Python 3.9.0.

Electric vehicles are growing in popularity and are reviving a much disused powertrain in the vehicle sector. This paper deals with the measurement of driving performance of electric vehicles. For twelve selected vehicles, the parameters given by the vehicle manufacturer and measured during individual runs were compared. The measurements were carried out on a predetermined route, divided into several parts. The data obtained here not only serve to compare the parameters, but also to determine the degree of dependence of the individual measured parameters on the range of the vehicles.

Presented paper deals with determination of dynamic stiffness of rubber bushing. Viscoelasticity of rubber is introduced. Next rheological models are shown and determined. Theory of the viscoelastic constitutive relation are done with storage modulus and loss modulus. Rubber bushing FEM model was prepared for calculation of dynamic stiffness through dynamic harmonic analysis in MSC Marc. Results from simulations are compared to experimental measurement data.

This paper deals with the method of creating a virtual autonomous vehicle dynamics model SimRod in AMESim environment and implementing such a model in Prescan and MATLAB/Simulink environments and performing co-simulation of the vehicle cornering maneuver at different values of the grip factor in these software. As a result, the driving dynamics of the SimRod vehicle is assessed in the simulation environment and the stability of the vehicle in the turn with respect to the grip factor and vehicle speed is analyzed.